Characteristics of suspended particles in a small stormwater pond

Paper in proceeding, 2002

Polluted urban stormwater contains a number of hazardous constituents, such as heavy metals and polycyclic aromatic hydrocarbons (PAH). These pollutants are to a considerable extent associated with solids and can therefore be removed from the stormwater through sedimentation and particle encounter on aquatic vegetation. Due to this fact, stormwater ponds have frequently been used as a method for the treatment of stormwater. Information regarding particle characteristics and associated pollutants in stormwater is therefore of great importance to engineers involved in the design of ponds. This study investigates the inflow particle characteristics (such as particle size distribution, total and volatile suspended solids content and heavy metal content) of a small stormwater pond that predominantly receives stormwater drainage from a highway. Flow measuring devices and two automatic samplers were installed at the inlet and outlet of the pond. Measurements of particle characteristics and pollutant loads at the pond inflow and outflow for several storm events are carried out. The results show the particle volume in the stormwater (particle volume per stormwater volume) predominately consists of very fine particles and that the smallest particles comprise most of the surface area. Densities of particles in the inflow stormwater are presented. The stormwater pollutants exhibit strong correlation with particle characteristics, which is of great importance for pond design.